1. Field of the Invention
The present invention relates to an A/D-conversion circuit, a temperature-sensor circuit, an integrated circuit, and a method of adjusting the temperature-sensor circuit.
2. Description of the Related Art
As for an A/D-conversion circuit, which converts an analog voltage into a digital value, various types such as an integration type and a successive approximation type have been used conventionally.
However, not much consideration has been given to noise generated in analog voltage for conventional A/D-conversion circuits.
Moreover, as for a display control circuit for a display unit using an electro-optical element, a control that takes into consideration temperature dependency characteristics of the electro-optical element is needed. Taking a liquid crystal as an example of an electro-optical element, transmissivity of a liquid crystal varies even when the same voltage is applied, as environmental temperature varies. Therefore, a display control circuit needs to apply a voltage corresponding to environmental temperature to a liquid crystal by conducting temperature compensation. For this reason, it is preferable to embed a temperature-sensor circuit in the display-control circuit. Thus, an A/D-conversion circuit for recognizing the environmental temperature is needed in such a temperature sensor circuit. However, it turned out that there have been cases that noise causes errors in the A/D conversion results in A/D-conversion circuits used for such a temperature sensor circuit.
The present invention has been made in view of the above technical problem, and an object thereof is to provide an A/D-conversion circuit, which does not easily malfunction even if noise is generated, a temperature-sensor circuit and an integrated circuit containing the same A/D-conversion circuit, and a method of adjusting the temperature-sensor circuit.